Tune in to the race coverage nice and early to see a re-creation of the historic Le Mans running start. At 14:15 local time (45 minutes before the flag drops), the cars will be line up along the side of the track, ready for the drivers to sprint across the straight and jump in.

The chances of 55 drivers adhering correctly to the careful choreography are about as high as those of all 55 cars finishing the race.

2. A race-changing downpour

The beauty of Le Mans is that even though the race lasts 24 hours, things can turn upside down in an instant. This year, perhaps more so even than in 2008, Audi could do with a storm to give it an opportunity to ruffle Peugeot's feathers.

If the heavens do open, try to keep up with the chaos down the order as all four classes attempt to come to terms with the changing conditions with varying levels of driver confidence and competence.

3. The token pitstop calamity

There's always one. Last year it was Peugeot - releasing Pedro Lamy into the path of the Pescarolo-run 908. The works car punctured a tyre in the impact, which then blew on the Mulsanne Straight, and it was two laps down before the first hour was run. Whose turn is it this year? Chevrolet has probably got its embarrassment out of the way already, after its two cars crashed into each other at Sebring.

4. Getting lost in the night

Even in these days of ground-breaking technology, blanket coverage, live timing, onboard cameras, limitless telemetry and reliable pit-to-car radios, you still can't account for the odd car just going missing in the night.

Look out for a perplexed crew in the pitlane, peering back at the entry and shrugging shoulders at each other as another minute ticks by without their car coming round or word from their driver.

5. Clashes in traffic

With so many cars, with varying degrees of driver talent and car performance, it's inevitable that a prototype will fall over a GT car. The question is: will it involve a leading contender?

6. #2 Peugeot to not break

Peugeot's hare line-up hasn't had much luck come the race. Stephane Sarrazin had taken three poles in a row prior to this year's race, but a string of problems has prevented it from getting anywhere near a win. Its charge was crippled by overheating problems in '08 and a broken disc bell gave last year's event to the steady car.

This year Sarrazin and Montagny have swapped Bourdais for Minassian. Is it finally time for the fancied car to make it through unscathed?

7. Davidson and Pagenaud in factory 908s

Anthony Davidson and Simon Pagenaud are the new boys in the Peugeot line-up this year. Both have fine sportscar pedigrees, with Davidson doing an excellent job with Aston Martin last year and Pagenaud earning his big break thanks to some outstanding drives alongside last year's winner David Brabham at Highcroft in the American Le Mans Series.

Both have bolstered their respective cars (Davidson with Alex Wurz and Marc Gene, and Pagenaud with Bourdais and Lamy) giving Peugeot comfortably the strongest roster and three cars with a very real chance of winning.

8. ORECA Peugeot vs the factory cars

As if three works 908s with genuine victory hopes wasn't enough, the ORECA-run customer Peugeot is in the hunt as well. And while it's tough for anyone to match the factory line-up, Nicolas Lapierre, Olivier Panis and Loic Duval are about as close as anyone gets.

The #4 car has been so comfortably clear of the Audis during the build-up that its only aim for the race has to be to challenge for victory outright. But will it be allowed to?

9. Is there any race pace in the R15 plus?

Audi never goes all out in qualifying, meaning its cars are invariably a lot closer in the race. On qualifying speed, there are genuine fears that Peugeot will clear off and it won't be much fun for anyone else. But hold out hopes that all the talk of working on race set-up and tyre management is true, and the R15s just might be able to make a race of it.

10. McNish's mega stint

One of the reasons that Audi generally stays in touch longer than expected in the race is its Allan McNish card. The team seems to have one particularly mega stint that the Scot gets to use once in each race.

Two years ago it was his unfathomable speed in the early hours of Sunday morning that set up an Audi win against the odds. Even if victory is out of reach, look out for the superhuman stint that prolongs the inevitable - that you know only a handful of drivers in the world would be capable of.

11. #9 Audi being faster than you thought

Mike Rockenfeller has new company in the 'junior' Audi this year, joined by the highly-rated Romain Dumas and Timo Bernhard. The three know each other well from their Porsche days and together are the closest thing Audi have had to matching the legendary Kristensen/McNish/Capello line-up in some time.

12. Petrol battle not materialising

Leading into this week, hopes were high for a hard-fought thrash between the leading petrol-powered cars for honours in the unofficial class. But the Lola-Aston Martins have emerged without much opposition - even they're wondering where their rivals have gone.

Ahead of the start, the ORECA car looks to be the only one likely to pose a threat. The two Rebellion Lolas promised much but have had a woeful week so far. The Drayson Lola hasn't quite featured yet either.

13. Fernandez the deciding factor in #007

The #007 AMR car looks most likely to take petrol honours, but its chances of success will rest largely with Adrian Fernandez and how he settles in alongside Stefan Mucke and Harold Primat.

If Fernandez can get close to Mucke's pace, the car will be fast and tough to beat. If he's nearer to Primat's (respectable but not special) times, the car risks being jumped by the stronger Rebellion or ORECA line-ups.

14. Marco Andretti's Le Mans debut

The Andretti name should have won Le Mans. Mario came close on several occasions and Michael had two pretty good stabs. Marco isn't going to win it this year, of course. But he has been genuinely impressive so far, alongside team-mates who know the car and the circuit inside out.

The Rebellion team may well have struggled so far, but the third generation of the Andretti family's adventure at Le Mans starts here.

15. Greg the fastest Mansell

The Mansell Ginetta-Zytek is another of the petrol P1 contenders that hasn't been on the pace so far, but the two primary pedallers are tasting the circuit for the first time. So far, youngest son Greg has out-paced his old man pretty consistently, though it'll be another challenge to repeat that in race trim - through the traffic and his first experience of night racing.

16. Highcroft walking LMP2

David Brabham knows the Highcroft HPD as well as any driver here knows his tools, and as last year's race winner he ought to know his way around the eight miles too.

With the handy team-mates of Marco Werner and Marino Franchitti, the car should remain in good hands at all times - while the rival Strakka car will only compete with it until Nick Leventis gets in. Having never done a 24-hour race before, the obvious question mark is over the HPD's ability to run for the duration without breaking.

17. LMP2 race of attrition as usual

You might have hoped that the arrival of the HPDs (Acuras, to you and me) would beef up the LMP2 class to the point of making it an actual competition. But no. The arrival of HPD has unfortunately synced with the departure of Porsche, so things are a bit thin on the ground again.

The RML Lola will be in the ballpark if anything happens to the HPDs and the ASM Ginetta-Zytek and one of the Oak cars has a decent line-up. But you can't help but fear that the last car not to run into problems will win.

18. GT2 to beat GT1

While on the subject of classes that aren't as good as they should be; watch out for GT2 beating GT1. It will need the Young Driver Aston Martin to run into problems for a GT2 car to beat the entire GT1 class, but there are reliability concerns over the majority of them.

Keep count of how many GT1 cars can manage to keep the flat-out, battling GT2 machines behind them.

19. Ford taking the fight to Aston Martin

It's probably a bit of an ask for the Alphand Corvettes to have a go at the Aston for GT1 honours, so hopes of a good race may rest with Ford on its return. The line-up in the first Matech GT40-style car, which includes ex-Renault Formula 1 racer Romain Grosjean, looks strong enough to be a contender.

It's great to see the legendary shape back at La Sarthe, but the new GT is another unproven quantity over this distance.

20. The return of the JLOC Lamborghini

Believe it or not, it's back. To put it mildly, the Japanese Lamborghini Owners' Club team hasn't had a great last couple of visits to Le Mans. It has a new Murcielago this year and surprised many people by completing a significant number of laps this week without breaking down.

Still, if you had to put money on the race's first retirement - this wouldn't be the worst shout.

21. Chevrolet's GT2 pace

The realigned Corvette GT2 car finally has a truck load of opposition to go up against, rather than its two cars having to settle for squabbling with each other in GT1 (as in '09) or just with Aston Martin ('08).

The cars look quick so far, walking straight into the thick of the ongoing war between Ferrari and Porsche. With the Le Mans experience of its driver roster and team personnel, expect the yellow cars to go the distance with the class leaders.

22. Jean Alesi and Giancarlo Fisichella

Alesi has raced at Le Mans before, although that was now 21 years ago, and Fisichella is here for the first time. They are two big names but whether they can get to grips with the Ferrari 430 quickly enough to be a force in the ultra-competitive GT2 class remains to be seen.

The presence of Toni Vilander in the line-up will ensure that the sole remaining AF Corse car starts in the right direction. It'll be up to the F1 veterans to keep it there.

23. BMW getting closer

Early in the week BMW had all but given up hope. Its two M3s started more than five seconds off the pace of the class leaders, having been stumped by the enforced smaller restrictor and redesigned rear suspension, thanks to the ACO.

But there was serious progress on Thursday and Farfus brought the #78 car to within 2.5s of the class-leading Risi Ferrari. If BMW's habit of coming on stronger in races - and its endurance racing know-how from the Nurburgring - come into force, it could sneak a surprise result by Sunday afternoon. Keep an eye out for the livery on the #79 car too, it's a head-turner and is a throwback to the BMW Le Mans art cars of old.

24. Jaguar's Le Mans return

The big cat's Le Mans comeback has gone anything but to plan so far. The car looks a handful and has run far from smoothly during the week. After qualifying, it even trailed the JLOC Lambo in terms of deficit to its class leader. The team needs a clear run to progress with the XKR, but its reliability to date hasn't been particularly encouraging.

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